In bacteria, genetic information is transferred vertically because DNA is inherited by daughter cells. Genetic information can also be transferred horizontally, accounting in many cases for the exchange of genes that contribute to virulence and antibiotic resistance. Horizontal transfer is a major factor in the evolution of bacteria. An important route of horizontal transfer is by the release of DNA into the environment and the subsequent uptake of this DNA by bacteria, a process known as transformation. The work proposed in this application is devoted to obtaining a mechanistic understanding of the transformation process. We wish to learn how cells bind DNA to their surface and how they internalize this DNA, the role of a filamentous structure known as the pseudopilus in the uptake process and to use microscopy to visualize the uptake and processing of the DNA once it is internalized as well as the interaction of the DNA with the recipient cell chromosome. Cells that are capable of being transformed are in a physiological state in which their growth, division and DNA replication are halted. We will continue our efforts to understand the causes of this arrest and the mechanisms that enable the cells to eventually resume growth.